ABSTRACT This SBIR Phase I proposal requests $162,464 support for Advantage Silver Dental Arrest, LLC. to develop and assess the technical and scientific feasibility of Silicon Dioxide Encapsulated Silver Diamine Fluoride (E- SDF) as a commercial product to arrest dental caries. The goal is to regulate the dosage of SDF to caries lesions by way of encapsulating SDF in pH-sensitive silicon dioxide (SiO2) capsules, such that the amount of SDF delivered controlled to occur at pH values in carious lesions per se; and, thus, is minimized with respect to the entire tooth surface, while remaining caries inhibitory. The product will be an aqueous suspension of E- SDF, with an adjustable concentration, that can be applied to decayed enamel and dentin. The treated surface will then be coated with sodium fluoride varnish to assure E-SDF contact to lesions and increase contact time. This will both harden and make less soluble the inorganic substance of the softened dentin. By limiting release of SDF to specific low pH environments, application will cause less staining than the 38% SDF currently available in the US. This proposal responds to NIDCR topics: F. Develop ways to interfere with microbial colonization and growth through the use of antimicrobial agents and chemotherapy and **D. Develop and test for safety, efficacy, and/or effectiveness of measures or materials for diagnosing, preventing, or treating oral, dental, and craniofacial conditions and disorders. The aims: 1) Construct E-SDF through coupling processes of emulsification and established sol-gel chemical reaction methods. 2) Demonstrate that E-SDF lyses at ?pH 5.5, and not at less acidic (higher) pHs, and when release occurs, to characterize the kinetics of the release from E-SDF of SDF. 3) Compare the released SDF after lysis of E-SDF with aqueous SDF. 4) Determine the effects of E-SDF on Streptococcus mutans and homofermentative lactobacilli. 5) Evaluate in vitro the mineral content and physical properties (hardness and color) of dentin caries lesions in human tooth blocks treated with E-SDF soon after treatment and after being stored in artificial saliva for 1 week. The topical agent envisioned by Advantage Silver Dental Arrest, LLC builds on the current mainstay of caries arrest, aqueous 38% SDF, but increases its safety and reduces the side effect of staining. E-SDF will be inexpensive, easy to use, and well tolerated by patients of all ages and special needs. This effort brings partners with a strong record in materials physics, microbiology, caries research and public health together with oral care industry partners who have a history of successfully bringing products to market. This research addresses Healthy People 2020 OH-1 Reduce the proportion of children and adolescents who have dental caries experience in their primary or permanent teeth. The size of the United States topical fluoride market is estimated to total $185 - $205 million annually. We conservatively expect to capture between 5% and 10% of the U.S market 3 years post 510k clearance. Key words: dental caries; diamine silver fluoride; silicon dioxide; topical agent